Sewing machine loop-takers



Maw L w56 G. G. RUEMMLER 23.7%689 SEWING MACHINE LOOP-TAKERS Filed Feb. 2, 1954 V V H Fig 6 36 l5 Tn le Tb 4o /\4 I4 32 L l] I/ I Mw/ I 25 1 f u i n l5 22 27 x "54 F @A i \f\ 2e Y 36 o f 24 l 'O F|g.3 3o 3T 25 Il .UWE/wok.

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ATTORNEY SEWING MACHENE LOP-TAKERS Gerhard G. Ruernrnler, Roselle, N. J., assigner to The Singer Manufacturing Company, Elizabeth, N. l., a corporation of N ew `lersey Application February 2, 1954, Serial No. 407,676

l Claims. (Cl. 112-228) This invention relates to loop-takers for lock-stitch sewing machines, and more particularly, to a hook construction including a yielding raceway for a bobbin-case carrier.

lt is an object of this invention to provide a yielding raeeway construction for the bobbin-case carrier ot a circularly moving hook which is quiet and long wearing in operation.

It is also an object of this invention to provide a yielding raceway construction for a circularly moving hook which operates not only to facilitate the clearing of the thread which may have become jammed between the bobbin-case carrier and the hook body, but which also acts to prevent such jamming. p

With the above and other objects and advantages in view, as will hereinafter appear, this invention comprises the devices, combinations and arrangements of parts hercinatter described fand illustrated in the accompanying drawings of a preferred embodiment in which:

Fig. 1 is an end elevational View of a rotary hook together with a portion of the sewing machine bed and the needle, showing a rotary hook shortly after having seized the needle-thread loop.

Fig. 2 is an end elevational view similar to Fig. 1 and showing the needle-thread loop being carried about the bobbin case by the rotary hook.

Fig. 3 is an end elevational View similar to Fig. l, but showing the position of parts as the needle-thread loop is cast oit the beak of the rotary hook.

Fig. 4 is an enlarged cross-sectional view of the hook body and the gib taken substantially along line 4--4 of Fig. 3.

Fig. 5 is an enlarged sectional view of a portion of the hook body taken substantially along line 5-5 of Fig. l.

Fig. 6 is an enlarged sectional View of a portion of the hook body and the bobbin-case carrier taken substantially along line 6-6 of Fig. 1.

The rotary hool; which is illustrated in the drawings and to which this invention is applied is of the type adapted to complete two revolutions for each cycle of needle reciprocation in the formation of each stitch. The mode of attaining the necessary timed actuation of the needle and the hook does not form a part of this invention. These stitch-forming instrumentalities may be actuated in a manner well known in the sewing machine art as disclosed, for instance, in the U. S. patent of Peets, No. 2,617,375, Nov. 1l, 1952.

In Figs. 1, 2 and 3, the rotary hook is illustrated in completely assembled form, i. e., with hook-body l0 as shown separately in Fig. 4, a bobbin-case carrier 11, of which a portion is illustrated in Fig. 6, and a bobbin case 12. In each of the Figures 1, 2 and 3 the hook is depicted in a different position during a typical stitch forming cycle for the purpose of illustrating the thread concatenation during the period in which jamming of the thread in the hook mechanism is most apt to occur.

In these figures, a fragment of a sewing machine bed rates Patent 2,743,689 Patented May 1, 1956 is shown as at 13. Fitted on the bed is a throat-plate 14 and a stop member 15 which is bifurcated to accommodate a rotation-restraining finger 16 which projects from the bobbin-case carrier lll. These iigures also include a fragment of a needle 17 and indicate the needle thread at Tf1. and the bobbin thread at Tb. As is well known in the sewing art, the lower thread mass is wound on a suitable bobbin (not shown) which is disposed within the shell-like bobbin case l2.. The bobbin case is formed with. a latch lever 18 by which the case may be releasably secured to a center post i9 projecting from the bobbincase carrier lli. The restraining linger 16 thus prevents the carrier, the bobbin case and the bobbin from rotating with the hook body It), and the bobbin with its thread mass will rotate only as the thread is pulled therefrom and fed into the seam being stitched. Apart from this periodic rotation incident to unreeling, the bobbin remains stationary in the sense that it does not rotate with the hooi; body and the terms stationary or nonrotary thread mass will be used in the following specication with that connotation.

The ro-taryhook body lll, which is best illustrated in Fig. 4, is generally cup-shaped so as 'to partially envelope a non-rotary thread mass about which the hook casts a loop of needle-thread during each stitch. To this end, the hook body is provided with a sidewall 2i) formed with a slabbed portion or fiat seat 2l which terminates as at 22 and is designed to accommodate a gib member 23. The hool; body sidewall 20 extends from the slabbed portion 21 to a loop-seizing beak 24 and. is formed with a prominent rib-like portion 25' which extends from the beak 24 to a linger 26 which, as best illustrated in Fig. 5, overlies the slabbed portion and is in spaced relation thereto to form a gib-receiving slot 2.6'. The tinger 26 thus forms a gib-gripping clamp which urges the gib firmly against the slabbed portion 2l of the hook body. The rib-like portion 25 adjacent the beak 24;- is formed with an inclined outer surface 27 which is adapted to control the needle thread-loop during stitch formation. Defined between the loop-seizing beak 24 and the terminus 22 of the slabbed portion 2l. is a gap 2.3 in the hook body sidewall 2li which serves, as will be hereinafter described, to accommodate the passage of needle thread about the stationary under thread mass carried within the cupshaped hook body.

The stationary bobbin-case carrier ll is supported relative to the rotary hook body ill by a bearing arrangement comprising an annular bearing rib 30 formed on the bobbin-case carrier, and a cooperating raceway formed in the hook body. The raceway comprises an annular inner bearing surface l1 formed in the sidewall of the hook body. In the preferred embodiment, this inner bearing surface 3l is continuous except for the gap 28 in the sidewall, An outer bearing surface of the hook-body raceway is provided in two separate increments about the periphery of the hook body; the rs't increment 32 s comparatively short and is formed as an integral part of the sidewall 2@ by a lip which extends adjacent the hook beak 2d. The second and larger increment is provided by the gib member Z3 which overhangs the slabbed portion 2l of the hook body sidewall and thereby serves to connue the bobbin-case carrier bearing rib 30 in place against the continuous inner bearin surface 3l of the racehe bearing rib 3l? of the bobbin-case carrier is formed with a gap 3ft which serves, as is well known in the art, to cooperate with the gap 2S in the hook body sidewall to admit and to release one limb of the needle-thread loop for passage between the bobbin-case carrier and the hook body.

Figs. 1, 2 and 3 best illustrate the manner in which the hook operates to carry a loop of needle-thread about the `stationary under thread mass. In Fig. l, the parts are shown in a position immediately following the seizure of the needle-thread loop by the hook beak 24. ln this View, the needle-thread loop Tn is being carried by the hook beak into engagement with the pointed extremity of a loop-retaining shoulder 34 of the bearing rib of the stationary bobbin-case carrier. This pointed extremity 34 borders the gap 33 in the bearing rib. The needle-thread loop is detained by the pointed extremity 34 so that upon continued rotation of the hook to the position of Fig. 2, the limb of needle-thread loop T11 from the hook beak to the eye of the needle is drawn downwardly about the hook and cammed forwardly over the face of the bobbin-case by the inclined outer surface 27 of the hook body adjacent the hook beak.

Upon continued rotation of the hook to the position illustrated in Fig. 3, the take-up serves to draw up the needle-thread loop oil the hook beak and continues to draw the thread-loop around the stationary bobbin, The gib member 23 serves at this point in the stitch-forming cycle to confine the needle-thread loop after the loop is discharged from the hook beak so as to prevent twisting or other abnormal concatenation of the thread. It will be noted in Fig. 3 that the needle-thread loop, having been carried about the lower thread mass, is still not free of the bobbin-case carrier bearing rib and will not be free thereo't` until a position is reached in which the gap 33 in the bearing rib registers with the gap 28 in the hook body sidewall to provide an opening for escape of the needlethread loop. The needle-thread loop will then have been carried completely about the bobbin-thread Tb and will be free to be drawn up over the rotation-restraining nger and to be set into the work fabric.

In the above described mode of operation and incident to the admission and release of the needle-thread loop between the bobbin-case carrier bearing rib and the hook body raceway, circularly moving loop-takers such as rotary hooks are known in the art to be susceptible to jamming which is caused by the needle-thread loop becoming caught and wedged between the bearing rib and the raceway. lt has been recognized heretofore that by making the raceway yieldable, the difhculties which are normally encountered with hook jamming may be lesscned. However, prior art hooks having yielding raceways have exhibited many disadvantages. They have been uniformly far more costly to manufacture than hooks without this feature, in fact, most have been prohibitively expensive. They have been noisy in operation since the bobbin-case carrier is not confined rmly in the raceway. They have lacked durability not only because of the many delicate springs and other parts involved but because of the wear incident to the loose ilexible fits between the parts. rln addition, many of these hooks actually proved to aggravate the very problem of hook jamming which they were designed to alleviate, because these raceways, being yieldable to permit jammed threads to escape therefrom, by the same token also encouraged entrance of the thread between the bearing rib and the raceway. in the hook of the present invention, all of these prior disadvantages have been overcome. Refering more particularly to Figs. and 6 of the drawings, the gib member 23 which cooperates with the inner bearing surface 3l. of the hook body to provide the largest portion of the raceway, is constructed and arranged to yield in a novel and advantageous manner. The gib member 23 is formed in the direction of rotation as indicated by arrows in Figs. l, 2 and 3 with a leading extremity' 35 which is adapted to extend into the slot 26' between the slabbed hook sidewall portion 21 and the overlying finger 26. At the opposite extremity the gib is formed with a tapered tail 36.

ln the preferred embodiment, the linger Z6 is annealed and bent toward the slabbed portion so as to clamp the gib member firmly against the hook body at a point adjacent the leading extremity of the gib. A locating screw 37 which is threaded into the hook body l@ is formed at its extremity with an unthreaded reduced portion 38 which extends into an aperture formed in the leading extremity of the gib. The gib member Z3, from the extremity of the finger 26 to the gib tail 36, is unsupported in a direction axially of the hook shaft, the flexibility of the relatively thin ilat gib being utilized to provide a yielding portion of the raceway. The gib, however, is contined in proper position on the slabbed hook body sidewall by a guide screw di) which is threaded into the hook body and which is provided with a shouldered head 41 which cooperates with a counterbored aperture 42 in the gib member to guide the gib during llexing thereof and also to provide a stop effective according to the clearance between the shouldered head 4l and the counterbore 42 to limit the maximum yielding of the gib member.

Since the direction of hook rotation is clockwise, as viewed in Figs. 1, 2 and 3, about the stationary bobbincase carrier, the danger of thread jamming into the raceway portion provided by the gib member 23 begins when the parts occupy a position as shown in Fig. l, i. e. when the pointed extremity 34 of the bearing rib is about to be received into the raceway in the hook body. During subsequent turning movement of the hook body, the leading extremity of the gib is prevented from yielding because it is clamped tightly against the slabbed sidewall by the linger 26. Entrance of needle-thread between the bearing rib and raceway is, therefore, discouraged at the leading extremity of the gib and the gib is free to yield only beyond the contines of the slot 26. Should the needlethread become wedged between the bearing rib and the raceway at any point along the gib member 23, continued rotation of the hook body in its normal direction of rotation will carry the jammed thread toward the gib tail. The gib, since it is clamped only at the leading extremity will yield in increasing amounts as the jammed thread progresses toward the gib tail as is shown in Fig. 6. In other words, the raceway of the present invention is designed to discourage thread from entering into the raceway but to facilitate clearing of any threads which do become jammed. Since the leading extremity of the gib is clamped firmly in place, it cooperates with the short raceway portion provided by the rst increment 32 of the raceway which is integral with the hook body sidewall to confine the bobbin-case carrier bearing rib in a positive manner and with a nice lit conducive to quiet hook operation and a minimum of wear.

Having thus set forth the nature of the invention, what l claim herein is:

l. A circularly moving loop-taker of the type adapted to cooperate with a stationary bobbin case having a peripheral bearing rib, said loop-taker comprising a body portion having raised sidewalls providing a bobbin case accommodating concavity, a flexible gib member defining with said sidewalls a yielding raceway for said bobbin case bearing rib, said gib member having a forward leading extremity and a rearward trailing extremity, means clamping the leading extremity of said gib member to said body portion sidewall, means guiding the trailing extremity of said gib member for yielding movements axially of said rotary loop-taker body portion, and a stop means limiting the extent of flexing of the free extremity of said gib member.

2. A circularly moving sewing machine loop-taker raving a body portion provided with a loop-seizing beak and with a segmental bobbin case accommodating raceway, said raceway comprising a segmental sidewall formed in said body portion and disposed in a plane normal to the axis of the circular motion of said loop-taker, a segmental gib having one extremity fixed to said body portion in spaced relation to said sidewall, and an opposite extremity yieldingly opposed to the sidewall of said raceway, said opposite extremity of the gib terminating in a loop-discharging tail, guide means confining Said loop-discharging tail of the gib to axial movements with respect to said loop-taker body portion, and a stop limiting outward movement of said gib tail in a direction away from the sidewall in the loop-taker body portion.

3. A circularly moving loop-taker of the type adapted to cooperate with a stationary bobbin case having a peripheraly bearing rib, said loop-taker comprising a body portion having raised sidewalls providing a bobbn case accommodating concavty, said side walls formed with a loop-seizing beak, a flexible gib member dening with said sidewalls a raceway for said bobbin case bearing rib, said gib member being formed at one extremity with a loop-controlling tail disposed to extend in a direction opposite that of said loop-seizing beak, means clamping the opposite extremity of said gib member to said looptaker body portion side wall, means guiding said loopcontrolling tail for yielding movements axially of said loop-taker body portion, and a stop means limiting the extent of flexing of said loop-controlling tail.

4. A circularly moving loop-taker of the type adapted to cooperate with a stationary bobbin case having a peripheral bearing rib, said loop-taker comprising a body portion having raised sidewalls providing a bobbin-case accommodating concavty, a flexible gib member defining with said sidewalls a yielding raceway for said bobbin case bearing rib, means rigidly securing one extremity of said gib member to said body portion side wall, a guidepin arranged between the free extremity of said gib member and said side wall, said guide-pin being disposed to confine said gib member for yielding movement axially of. said rotary body portion, and a stop means carried by said guide-pin for limiting the extent of ilexing of the free extremity of said gib member.

References Cited in the le of this patent UNITED STATES PATENTS 484,462 Rontke Oct. 18, 1892 1,996,324 Chiti Apr. 2, 1935 2,065,349 Southam et al Dec. 22, 1936 2,219,210 Rubel Oct. 22, 1940 

